1. Technical Field
This patent application relates to detection of objects such as a buried explosive device while operating from a moving platform.
2. Background Information
An electromagnetic device known as a super lens is capable of manipulating the near field of an antenna and focusing electromagnetic waves to resolutions beyond the diffraction limit. Numerous super lenses have been fabricated to operating from radio frequency (RF) wavelengths up to optical wavelengths. One approach described by Merlin, R., in “Radiationless Electromagnetic Interference: Evanescent-Field Lenses and Perfect Focusing”, Science, Volume 317, Issue 5840, pp. 927-(2007) uses grating like surfaces and arrays rather than volumetric structures. Subwavelength structures can control the near field, and are capable of focusing well beyond the diffraction limit, operating at arbitrary frequencies, forcing convergence to a spot on the focal plane.
It is also known that a synthetic aperture radar (SAR) is a form of radar system that uses relative motion between an antenna and its target region to provide distinctive long-term coherent-signal variations that are exploited to obtain finer spatial resolution than is possible with conventional beam-scanning means. See for example, the book by Fawwaz. T. Ulaby, Microwave Remote Sensing: Active and Passive, Volume II (Norwood, Mass.: Artech House, Inc., 1986). It is also known that the spatial resolution of a densely packed antenna array can be much smaller than the diffraction limit. Such “super gain” antennas are described in C. A. Balanis, Antenna Theory (3rd Edition) (Hoboken, N.J.: John Wiley & Sons, 2005) and/or R. E. Collin and F. J. Zucker (eds.), Antenna Theory, Part I (New York: McGraw-Hill, 1969). The entire teachings of these publications are hereby incorporated by reference.